Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.3.2.19 (ubiquitin-protein ligase)
 799 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The ubiquitin-protein ligase (E3), hRPF1/Nedd4, is a component of the ubiquitin-proteasome pathway responsible for substrate recognition and specificity. Although previously characterized as a regulator of the stability of cytoplasmic proteins, hRPF1/Nedd4 has also been suggested to have a role in the nucleus. However, in light of the cytoplasmic localization of hRPF1/Nedd4, it is unclear whether bona fide nuclear substrates of hRPF1/Nedd4 exist, and if so, what mechanism may allow a cytoplasmic ubiquitin ligase to manifest nuclear activity. Our search for nuclear substrates led to the identification of the human proline-rich transcript, brain-expressed (hPRTB) protein, the ubiquitination and degradation of which is regulated by hRPF1/Nedd4. Interestingly, hPRTB colocalizes with the splicing factor SC35 in nuclear speckles. Finally, we demonstrate that hRPF1/Nedd4 is indeed capable of entering the nucleus; however, the presence of a functional Rev-like nuclear export sequence in hRPF1/Nedd4 ensures a predominant cytoplasmic localization. Cumulatively, these findings highlight a nuclear role for the ubiquitin ligase hRPF1/Nedd4 and underscore cytoplasmic/nuclear localization as an important regulatory component of hRPF1/Nedd4-substrate recognition.
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PMID:Nuclear import/export of hRPF1/Nedd4 regulates the ubiquitin-dependent degradation of its nuclear substrates. 1134 38